1. Field of the Invention
The present invention generally relates to telephony communication techniques and, in particular, to a universal apparatus and method for interfacing signals with telephony networks that have different impedance characteristics.
2. Related Art
Telephony networks have been employed for many years to communicate voice and data signals across great distances. However, the impedance characteristics (e.g., AC line impedance, network balance impedance, DC line impedance, ringer impedance, etc.) of telephony networks unfortunately vary, sometimes significantly, from network-to-network. For example, the impedance characteristics of a telephony network in one country may be significantly different than the impedance characteristics of a telephony network in another country.
In this regard, an acceptable range of impedance characteristics of a telephony network is often regulated by the country in which the telephony network resides, such that any other telephony network in the same country should have similar impedance characteristics. However, the acceptable range of impedance characteristics varies from country-to-country. As a result, a telephony communication device (such as a telephone, modem, etc.) compatible with a telephony network in one country may not be compatible with a telephony network in another country, and successfully interfacing the communication device with a telephony network may only occur in one country or in a particular set of countries.
Due to the different impedance characteristics of telephony networks in different countries, manufacturers of telephony communication devices usually design the interface ports of communication devices on a country-by-country basis. In this regard, a manufacturer may design the interface port of a communication device assuming that the communication device will be interfaced with a telephony network having impedance characteristics within a particular range, as defined by the laws of a particular country. Typically, the communication device is then only sold in the particular country or in another country promulgating a similar range of impedance characteristics for telephony networks. If a user tries to use the communication device in a different country that promulgates a significantly different range of impedance characteristics for the telephony networks in that country, then it is likely that the communication device will not be operable. As a result, the use of each communication device produced by a manufacturer is usually limited to use within a particular country or to a particular set of countries having telephony networks with similar impedance characteristics.